A typical gallium nitride (GaN) device (e.g., a GaN transistor) is fabricated by depositing a nucleation layer over a base semiconductor substrate, and subsequently depositing a buffer layer over the nucleation layer, where the nucleation layer functions to initiate epitaxial growth of the buffer layer. After deposition of the nucleation, buffer, and channel layers, additional GaN material, other semiconductor layers, and other structures (e.g., gate, drain, and source contacts) are formed over the buffer layer to complete the device.
GaN on a base semiconductor substrate of silicon carbide (SiC) is a technology that is now used extensively in RF and microwave applications. Although GaN on SiC devices may have significant performance advantages over their silicon-based counterparts, a major drawback of GaN on SiC technologies is the extremely high cost of the base semiconductor substrate. Accordingly, GaN developers continually strive to develop less expensive GaN-based devices that still exhibit the superior performance advantages over analogous silicon-based devices.